[Inkscape-docs] manual page re animation

Hi Friends, I've just started working on a new page for the website, about animation and Inkscape. So I was looking at the info in the manual, and I noticed this page: http://tavmjong.free.fr/SVG/ANIMATION/. The illustration in the middle section of that page, Animation and CSS, doesn't seem to work with Firefox. The other 2 illustrations do show the animation when I click on them. But nothing with the one in the middle. Note that the image is animated on click, in IE11. Is this a known problem -- with the manual or with Firefox? Should make bug report in LP Documentation account?

Thanks for your help, brynn